The present invention relates in general to the field of operating devices for illuminants, for example, gas discharge lamps or light emitting diodes (LEDs).
In different areas of application within lighting technology, especially in the field of LEDs, OLEDs and emergency lighting, there is a requirement to provide a galvanic isolation comparable with electronic transformers, so that the installation need not necessarily be implemented by a qualified technician. Accordingly, the light source and/or the electronic control circuit should operate on a potential galvanically isolated from the mains supply voltage.
The use of a two-stage approach is already known. In this context, a converter, which drives the illuminant, is controlled with potential isolation via a control circuit at the mains voltage side (primary side of the potential isolation). If feedback signals from the secondary side of the potential isolation, that is to say, especially from the region of the illuminant, are to be fed back to the control circuit, a potential isolation is also provided for this feedback. The control on the secondary side of the potential isolation is implemented through a further control circuit, which is one isolated from the first-named control circuit disposed at mains voltage potential.
From EP1608206A1, it is known that the control information can be transmitted in an electrically isolated manner, while the actual control circuit itself is not electrically isolated.